Added support for harper in markdown files (#5104)

doc/ale-markdown.txt

@@ -14,6 +14,35 @@ dprint                                                    *ale-markdown-dprint*
 See |ale-dprint-options| and https://dprint.dev/plugins/markdown
 
 
+===============================================================================
+harper                                                    *ale-markdown-harper*
+
+                                           *ale-options.markdown_harper_config*
+                                                  *g:ale_markdown_harper_config*
+                                                  *b:ale_markdown_harper_config*
+markdown_harper_config
+g:ale_markdown_harper_config
+  Type: |Dictionary|
+  Default: `{'harper-ls': {'diagnosticSeverity': 'hint', 'dialect': 'American', ...}}`
+
+  Dictionary passed to harper-ls as LSP workspace configuration. The default
+  enables spell check, sentence capitalization, repeated words, long
+  sentences, a/an errors, and spacing rules, and disables spelled-out numbers
+  and wrong-quote checks.
+
+  Example: >
+    let g:ale_markdown_harper_config = {
+    \   'harper-ls': {
+    \       'diagnosticSeverity': 'warning',
+    \       'linters': {
+    \           'SpellCheck': v:true,
+    \           'LongSentences': v:false,
+    \       },
+    \   },
+    \}
+<
+
+
 ===============================================================================
 markdownlint                                        *ale-markdown-markdownlint*
 

doc/ale-supported-languages-and-tools.txt

@@ -404,6 +404,7 @@ Notes:
 * Markdown
   * `alex`
   * `cspell`
+  * `harper`
   * `languagetool`!!
   * `markdownlint`!!
   * `marksman`

doc/ale.txt

@@ -3738,6 +3738,7 @@ documented in additional help files.
   markdown................................|ale-markdown-options|
     cspell................................|ale-markdown-cspell|
     dprint................................|ale-markdown-dprint|
+    harper................................|ale-markdown-harper|
     markdownlint..........................|ale-markdown-markdownlint|
     marksman..............................|ale-markdown-marksman|
     mdl...................................|ale-markdown-mdl|